Which of the following represents the correct solubility product expression for calcium phosphate?

In $1 \ L$ saturated solution of $AgCl$ $[K_{sp}(AgCl)=1.6 \times 10^{-10}]$,$0.1 \ mol$ of $CuCl$ $[K_{sp}(CuCl)=1.0 \times 10^{-6}]$ is added. The resultant concentration of $Ag^{+}$ in the solution is $1.6 \times 10^{-x}$. The value of $x$ is

Which of the following happens when $NH_{4}OH$ is added gradually to the solution containing $1 \ M \ A^{2+}$ and $1 \ M \ B^{3+}$ ions?
Given: $K_{sp}[A(OH)_{2}] = 9 \times 10^{-10}$ and $K_{sp}[B(OH)_{3}] = 27 \times 10^{-18}$ at $298 \ K$.

$A$ solution which is $10^{-3} \ M$ each in $Mn^{2+}, Fe^{2+}, Zn^{2+},$ and $Hg^{2+}$ is treated with $10^{-16} \ M$ sulphide ion. If $K_{sp}$ of $MnS, FeS, ZnS,$ and $HgS$ are $10^{-15}, 10^{-23}, 10^{-20},$ and $10^{-54}$ respectively,which one will precipitate first?

Which of the following is a sparingly soluble salt?

The values of $K_{sp}$ of two sparingly soluble salts $Ni(OH)_2$ and $AgCN$ are $2.0 \times 10^{-15}$ and $6 \times 10^{-17}$ respectively. Which salt is more soluble? Explain.